1. Field of the Invention
The present invention relates to a float type drain trap and a method for discharging drain water.
2. Related Art
Conventionally, there are known a technology about a buoyancy type drain water discharging method and drain trap (for example, see JP-A-2005-180677 and JP-2012-077903).
According to JP-A-2005-180677, a drain trap is provided with a float having a float main body in its one end and floatable by water with an arm as its center, a rubber valve seat in the other end, and a rotation shaft in its central bent portion. A case including a case main body having a flow-in opening for receiving drain water therein and a discharge opening for discharging the drain water therefrom, a valve seat situated in the discharge opening, and a float bracket for holding the rotation shaft to allow the float to rotate are integrated to configure a case. By locating the rotation shaft in the float bracket in the case, when the drain water has not flowed up to a given position of the case, the rubber valve seat closes the valve seat by the dead load of the float. When the drain water has flowed to or beyond the given position of the case, the rubber valve seat opens the valve seat by the buoyancy of the float main body. In the drain trap, a magnet is interposed in any position of the arm between the float main body and the rotation shaft, and a partner member capable of generating an attraction force due to the magnet is disposed in any position inside the case. The rubber valve seat closes and opens the valve seat according to the relationship of moment to be determined by the dead load of the float, the buoyancy, the attraction force and the positions where they are generated.
According to JP-A-2012-077903, in a float type drain trap, a gas-liquid mixture of compressed air and drain water generated from the compressed air is received from a flow-in opening formed in an upper portion of a cover, and the drain water is separated from the gas-liquid mixture and is discharged from a discharge opening formed in a lower portion of a side wall. In the drain trap, a first permanent magnet constituting part of a float and a second permanent magnet constituting part of a valve are swung, when the first and second permanent magnets pass each other, there are generated mutually repelling magnetic power, and the repelling power opens and closes a valve seat connected to the discharge opening, whereby the drain water is discharged intermittently.
However, the above-mentioned conventional technologies have the following problems.
Firstly, in the drain trap using a conventional direct magnetic force system in the attraction power is generated because the magnet and partner member are directly attracted to each other, when they are attracted, strong magnetic force is generated but, when they are distant from each other even slightly, the magnetic force damps in reverse proportion to square of the distance. Especially, the magnetic force varies due to adhesion of foreign substances such as dust and dimensional errors, resulting in a problem that stable magnetic force cannot be obtained.
Next, since the float and rubber valve seat are formed integrally and thus the rubber seat valve operates correspondingly to the float, the degrees of opening of the valve seat are determined by the positions of the water surface through the float. Therefore, frequently, the valve seat opens half at an equilibrium point where the flow-in and discharge of the drain water coincide with each other, whereby the drain water is discharged while dripping successively. Further, since the magnetic force damps in reverse proportion to square of the distance, when the partner member is distant from the magnet even slightly, the partner member is easily out of the influential range of the magnetic force, which facilitate the generation of the equilibrium point. As a result, the drain water cannot be discharged energetically and intermittently, which makes it difficult to remove slime, dust and the like adhered to the small pores of the valve seat and the like.
Further, since the valve must be attracted with the negative pressure of the gushing of the compressed air discharged simultaneously with the drain water, the lowest water surface is situated at the discharge opening and thus the discharge of the compressed air cannot be stopped, resulting in the large loss of the compressed air.
In addition, in the conventional drain trap employing an indirect magnetic force system which uses the mutual repulsions of the magnetic forces respectively generated by the first permanent magnet constituting part of the float and the second permanent magnet constituting part of the valve when they are swung and are thereby caused to pass each other, when iron powder or the like is contained in the drain water, the magnets attract the iron powder, resulting in various troubles.